Authors:Daohong Liu; Zhirui Li; Guoqi Wang; Tongtong Li; Lihai Zhang; Peifu TangPages: 161 - 170Abstract: The aim of this study was to evaluate the virulence of Staphylococcus aureus in a controlled animal study using the standard sterile gauze and negative pressure wound therapy (NPWT), including activation of agr, gene expression and production of virulence foctors and depth of bacterial invasion. The tissue specimens were harvested on days 0 (6 h after bacterial inoculation), 2, 4, 6, and 8 at the center of wound beds. Laser scanning confocal microscopy was performed to obtain bioluminescent images which were used to measure the depth of bacterial invasion. The agrA expression of S.aureus and the transcription and production of virulence factors including Eap, Spa and α-toxin were significantly different. The bacterial invasion depth was significantly less with effect of NPWT. The markedly different activation of quorum sensing systems that enable cell-to-cell communication and regulation of numerous colonization and virulence factors result in distinct gene expression and pathogenicity over time in different microenvironment. Thus, the agr system represents a fundamental regulatory paradigm that can encompass different adaptive strategies and accommodate horizontally acquired virulence determinants.PubDate: 2018-02-01DOI: 10.1007/s10482-017-0938-zIssue No:Vol. 111, No. 2 (2018)

Authors:Joost Willemse; Ferhat Büke; Dino van Dissel; Sanne Grevink; Dennis Claessen; Gilles P. van WezelPages: 171 - 182Abstract: Streptomycetes are filamentous bacteria that produce a plethora of bioactive natural products and industrial enzymes. Their mycelial lifestyle typically results in high heterogeneity in bioreactors, with morphologies ranging from fragments and open mycelial mats to dense pellets. There is a strong correlation between morphology and production in submerged cultures, with small and open mycelia favouring enzyme production, while most antibiotics are produced mainly in pellets. Here we describe SParticle, a Streptomyces Particle analysis method that combines whole slide imaging with automated image analysis to characterize the morphology of submerged grown Streptomyces cultures. SParticle allows the analysis of over a thousand particles per hour, offering a high throughput method for the imaging and statistical analysis of mycelial morphologies. The software is available as a plugin for the open source software ImageJ and allows users to create custom filters for other microbes. Therefore, SParticle is a widely applicable tool for the analysis of filamentous microorganisms in submerged cultures.PubDate: 2018-02-01DOI: 10.1007/s10482-017-0939-yIssue No:Vol. 111, No. 2 (2018)

Authors:Sheng Wang; Biyao Mao; Mingxi Wu; Jingjing Liang; Le DengPages: 199 - 208Abstract: Biofilms are bacterial communities consisting of numerous extracellular polymeric substances. Infections caused by biofilm-forming bacteria are considered to be a major threat to health security and so novel approaches to control biofilm are of importance. Aptamers are single-strand nucleic acid molecules that have high selectivity to their targets. Single-walled carbon nanotubes (SWNTs) are common nanomaterials and have been shown to be toxic to bacterial biofilms. The aim of this study was to test whether an aptamer could play a role as targeting agents to enhance the efficiency of anti-biofilm agents. Hence, two complexes (aptamer–SWNTs and aptamer–ciprofloxacin–SWNTs) based on an aptamer which targets Pseudomonas aeruginosa and SWNTs were constructed. Both complexes were assessed against P. aeruginosa biofilms. In vitro tests demonstrated that the aptamer–SWNTs could inhibit ~36% more biofilm formation than SWNTs alone. Similarly, the aptamer–ciprofloxacin–SWNTs had a higher anti-biofilm efficiency than either component or simple mixtures of two components. Our study underscores the potential of aptamers as targeting agents for anti-biofilm compounds, as well as providing a new strategy to control biofilms.PubDate: 2018-02-01DOI: 10.1007/s10482-017-0941-4Issue No:Vol. 111, No. 2 (2018)

Authors:Zander R. Human; Casparus J. Crous; Francois Roets; Stephanus N. Venter; Michael J. Wingfield; Z. Wilhelm de BeerPages: 209 - 226Abstract: Actinomycete bacteria have previously been reported from reproductive structures (infructescences) of Protea (sugarbush/suikerbos) species, a niche dominated by fungi in the genera Knoxdaviesia and Sporothrix. It is probable that these taxa have symbiotic interactions, but a lack of knowledge regarding their diversity and general ecology precludes their study. We determined the diversity of actinomycetes within Protea repens inflorescence buds, open inflorescences, young and mature infructescences, and leaf litter surrounding these trees. Since the P. repens habitat is fire-prone, we also considered the potential of these bacteria to recolonise infructescences after fire. Actinomycetes were largely absent from flower buds and inflorescences but were consistently present in young and mature infructescences. Two Streptomyces spp. were the most consistent taxa recovered, one of which was also routinely isolated from leaf litter. Lower colonisation rates were evident in samples from a recently burnt site. One of the most consistent taxa isolated from older trees in the unburnt site was absent from this site. Our findings show that P. repens has a distinct community of actinomycetes dominated by a few species. These communities change over time and infructescence developmental stage, season and the age of the host population. Mature infructescences appear to be important sources of inoculum for some of the actinomycetes, seemingly disrupted by fire. Increased fire frequency limiting maturation of P. repens infructescences could thus impact future actinomycete colonisation in the landscape. Streptomyces spp. are likely to share this niche with the ophiostomatoid fungi, which merits further study regarding their interactions and mode of transfer.PubDate: 2018-02-01DOI: 10.1007/s10482-017-0942-3Issue No:Vol. 111, No. 2 (2018)

Authors:Wenchao Li; Xiaowei Guo; Linlin Shi; Junwei Zhao; Liangliang Yan; Xiaotong Zhong; Chen Zhang; Yufei Chen; Xiangjing Wang; Wensheng XiangPages: 227 - 235Abstract: A Gram-positive, non-motile actinomycete, designated strain NEAU-FJL1T, was isolated from tomato root (Solanum lycopersicum L.) collected from Harbin, Heilongjiang province, north China. The strain formed single spores with smooth surfaces from substrate mycelia. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain NEAU-FJL1T should be affiliated with the genus Plantactinospora and forms a distinct branch with its close neighbour Plantactinospora soyae NEAU-gxj3T (99.2% sequence similarity). The cell wall was found to contain meso-diaminopimelic acid and the whole cell sugars were identified as xylose, glucose, arabinose and galactose. The predominant menaquinones were identified as MK-10(H6) and MK-10(H4). The phospholipid profile was found to consist of diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylinositol. The major fatty acids were identified as C15:0, iso-C16:0, anteiso-C17:0, C17:0 and iso-C15:0. With reference to phenotypic characteristics, phylogenetic data and DNA–DNA hybridization results, strain NEAU-FJL1T can be distinguished from its most closely related strain and classified as a new species, for which the name Plantactinospora solaniradicis sp. nov. is proposed. The type strain is NEAU-FJL1T (= DSM 100596T = CGMCC 4.7284T).PubDate: 2018-02-01DOI: 10.1007/s10482-017-0943-2Issue No:Vol. 111, No. 2 (2018)

Authors:D. F. R. Cleary; A. R. M. PolóniaPages: 237 - 257Abstract: Anchialine lakes are a globally rare and unique ecosystem consisting of saline lakes surrounded by land and isolated from the surrounding marine environment. These lakes host a unique flora and fauna including numerous endemic species. Relatively few studies have, however, studied the prokaryote communities present in these lakes and compared them with the surrounding ‘open water’ marine environment. In the present study, we used a 16S rRNA gene barcoded pyrosequencing approach to examine prokaryote (Bacteria and Archaea) composition in three distinct biotopes (sediment, water and the mussel Brachidontes sp.) inhabiting four habitats, namely, three marine lakes and the surrounding marine environment of Berau, Indonesia. Biotope and habitat proved significant predictors of variation in bacterial and archaeal composition and higher taxon abundance. Most bacterial sequences belonged to OTUs assigned to the Proteobacteria. Compared to sediment and water, mussels had relatively high abundances of the classes Mollicutes and Epsilonproteobacteria. Most archaeal sequences, in turn, belonged to OTUs assigned to the Crenarchaeota with the relative abundance of crenarchaeotes highest in mussel samples. For both Bacteria and Archaea, the main variation in composition was between water samples on the one hand and sediment and mussel samples on the other. Sediment and mussels also shared much more OTUs than either shared with water. Abundant bacterial OTUs in mussels were related to organisms previously obtained from corals, oysters and the deepsea mussel Bathymodiolus manusensis. Abundant archaeal OTUs in mussels, in contrast, were closely related to organisms previously obtained from sediment.PubDate: 2018-02-01DOI: 10.1007/s10482-017-0944-1Issue No:Vol. 111, No. 2 (2018)

Authors:Yulia Boltyanskaya; Ekaterina Detkova; Nikolay Pimenov; Vadim KevbrinPages: 275 - 284Abstract: A search for the organisms responsible for the degradation of biomass of primary producers in Tanatar lakes resulted in the isolation of a novel anaerobic, haloalkaliphilic microorganism, strain Z-710T. The strain grows on proteinaceous substrates (peptides) but not on proteins. A rather limited range of substances of other classes can be utilised together with tryptone but not individually. An interesting physiological feature of the novel strain is a high capacity for hydrogen production (up to 30% v/v) during proteolytic fermentation. Phylogenetic analysis based on the 16S rRNA gene sequence similarity revealed that the organism can be assigned to the previously described genus Proteinivorax. According to its physiological features and the low DNA–DNA hybridisation level of the strain with the type strain of the only previously described Proteinivorax species—Proteinivorax tanatarense Z-910T—strain Z-710T is described here as representing a novel species with the name Proteinivorax hydrogeniformans sp. nov. The type strain is Z-710T (= DSM 102085T = VKM B-3042T).PubDate: 2018-02-01DOI: 10.1007/s10482-017-0949-9Issue No:Vol. 111, No. 2 (2018)

Authors:Carlos A. Araiza-Cervantes; Víctor Meza-Carmen; Guadalupe Martínez-Cadena; M. Isabel G. Roncero; Georgina E. Reyna-López; Bernardo FrancoPages: 285 - 295Abstract: The genome sequence of the plant pathogen Fusarium oxysporum f. sp. lycopersici contains a single gene encoding a predicted poly(ADP-ribose) glycohydrolase (FOXG_05947.2, PARG). Here, we assessed whether this gene has a role as a global regulator of DNA repair or in virulence as an ADP ribosylating toxin homologue of bacteria. The PARG protein was purified after expressing its encoding gene in Escherichia coli. Its inhibition by 6,9-diamino-2-ethoxyacridine lactate monohydrate and tannins was similar to its human orthologue that is involved in DNA repair. A deletion strain of F. oxysporum f. sp. lycopersici showed no growth defects and was not affected in pathogenicity. Together, our results indicate that the PARG protein of F. oxysporum f. sp. lycopersici is involved in DNA repair and does not act in pathogenicity as an effector.PubDate: 2018-02-01DOI: 10.1007/s10482-017-0951-2Issue No:Vol. 111, No. 2 (2018)

Authors:Jazmín Areli Álvarez Copado; Roberto Zazueta Sandoval; Areli Durón Castellanos; Felipe Padilla-Vaca; Bernardo FrancoPages: 297 - 309Abstract: Fungi are organisms capable of growing in a myriad of conditions and respond to counteract environmental cues. Several locations in the world are polluted with oil and its derivatives, and some microorganisms tolerant to these compounds have been isolated. Some fungi can grow in the presence of molecules such as polycyclic aromatic hydrocarbons as sole carbon sources. In this report, we further characterized the induced enzymes with phenanthrene from Mucor circinelloides YR-1 strain, isolated from a polluted field near a petrochemical facility in México. We identified a putative oxidase that is induced when growth with phenanthrene as sole carbon source at a pH of 8.5 and is NADP+ dependent. We show that this enzyme bears naphthalene dihydrodiol dehydrogenase activity with substrate preference for the cis-naphthalene over the trans-naphthalene, with an optimal pH in the range of 8–10. Mass spectrometry analysis revealed that the induced enzyme belongs to the NADP+ oxidase family enzymes with the typical Rossmann-fold for NADP+ binding. This enzyme seems to form a high molecular weight structure (~ 541 kDa) and with a monomer of 57 kDa, suggesting that the multimer is constituted of 10 subunits. Our findings contribute to understanding of the roles that dihydrodiol dehydrogenases have in organisms exposed to toxic compounds in the environment and can regulate their expression.PubDate: 2018-02-01DOI: 10.1007/s10482-017-0950-3Issue No:Vol. 111, No. 2 (2018)

Authors:Bruno Senghor; Hubert Bassène; Saber Khelaifia; Catherine Robert; Pierre-Edouard Fournier; Raymond Ruimy; Cheikh Sokhna; Didier Raoult; Jean-Christophe LagierAbstract: A Gram-positive, moderately halophilic bacterium, referred to as strain Marseille-P3518T, was isolated from a stool sample with 2% NaCl concentration from a healthy 15-year-old male living in Dielmo, a village in Senegal. Cells are aerobic, rod-shaped and motile and display endospore formation. Strain Marseille-P3518T can grow in a medium with 0–20% (w/v) sodium chloride (optimally at 5–7.5% w/v). The major fatty acids were 12-methyl-tetradecanoic acid (45.8%), 13-methyl-tetradecanoic acid (26.9%) and 12-methyl-tridecanoic acid (12.8%). The genome is 4,347,479 bp long with 42.1% G+C content. It contains 4282 protein-coding and 107 RNA genes. Phylogenetic analysis based on 16S rRNA gene sequence comparisons showed that strain Marseille-P3518T is a member of the Bacillaceae family and is closely related to Sediminibacillus albus (97.4% gene sequence similarity). Strain Marseille-P3518T was clearly differentiated from its phylogenetic neighbors on the basis of phenotypic and genotypic features. Strain Marseille-P3518T is, therefore, considered to be a novel representative of the genus Sediminibacillus, for which the name Sediminibacillus massiliensis sp. nov. is proposed, and the type strain is Marseille-P3518T (CSUR P3518T, DSM69894).PubDate: 2018-02-07DOI: 10.1007/s10482-018-1032-x

Authors:Imen Nouioui; Lorena Carro; Vartul Sangal; Marlen Jando; José Mariano Igual; Michael Goodfellow; Hans-Peter KlenkAbstract: The taxonomic positions of two fast growing mycobacteria (CECT 8778T and CECT 8779T) were established using a polyphasic approach. The strains were shown to have chemotaxonomic, cultural and morphological properties consistent with their classification in the genus Mycobacterium. Multi-locus sequence analyses (MLSA) show that strain CECT 8778T forms a well-supported clade together with the type strains of Mycobacterium aurum, Mycobacterium austroafricanum and Mycobacterium vanbaalenii while strain CECT 8779T presents as a distinct branch that is well separated from its near phylogenetic neighbours; it is also apparent from the MLSA genetic distances that these strains are most closely related to the type strains of Mycobacterium mageritense and M. vanbaalenii, respectively. Digital DNA:DNA hybridization and average nucleotide identity values between each of the strains and its close phylogenetic neighbour are below the 70 and 96% threshold values for definition of prokaryotic species; these results are underpinned by corresponding phenotypic data. Based upon the consensus of the phenotypic and phylogenetic analyses, it can be concluded that the two strains represent novel species within the genus Mycobacterium for which the following names are proposed: Mycobacterium neglectum sp. nov., with the type strain CECT 8778T (BN 3150T = DSM 44756T) and Mycobacterium palauense sp. nov., with the type strain CECT 8779T (= DSM 44914T).PubDate: 2018-02-05DOI: 10.1007/s10482-018-1029-5

Authors:Aravind Sundararaman; Sathiyaraj Srinivasan; Jong-Hoon Lee; Sang-Seob LeeAbstract: A Gram-positive, motile, endospore-forming, rod-shaped bacterium, designated strain M2024T, was isolated from Myeolchi-jeotgal, a traditional Korean high-salt fermented anchovy and was characterised using a polyphasic taxonomic approach. Comparative 16S rRNA gene sequence analysis showed that strain M2024T belongs to the genus Lentibacillus in the family Bacillaceae of the Firmicutes. The 16S rRNA gene sequence analysis showed that strain M2024T is closely related to Lentibacillus populi WD4L-1T (95.5%), Lentibacillus garicola SL-MJ1T (95.2%) and Virgibacillus siamensis MS3-4T (95.1%). The chemotaxonomic properties of strain M2024T are consistent with those of members of the genus Lentibacillus: the quinone system has MK-7 as the predominant menaquinone and anteiso-C15:0 and anteiso-C17:0 are the predominant cellular fatty acids. The major polar lipids were identified as diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. The G+C content of the genomic DNA was determined to be 36.2 mol%. Differential phenotypic properties compared with closely related type strains support the conclusion that strain M2024T can be separated from previously described members of the genus Lentibacillus. The strain thus represents a novel species in this genus, for which the name Lentibacillus alimentarius sp. nov. is proposed. The type strain is M2024T (= KEMB 9001-124T = JCM 16521T).PubDate: 2018-02-03DOI: 10.1007/s10482-017-1006-4

Authors:Li Ma; Shuai Chao Zheng; Ti Kun Zhang; Zi Yi Liu; Xue Jian Wang; Xing Kui Zhou; Cheng Gang Yang; Jin Ling Duo; Ming He MoAbstract: Accumulated evidence suggests that root exudates have a major role in mediating plant–microbe interactions in the rhizosphere. Here, we characterized tobacco root exudates (TREs) by GC–MS and nicotine, scopoletin, and octadecane were identified as three main components of TREs. Qualitative and quantitative chemotaxis assays revealed that Pseudomonas aeruginosa NXHG29 with antagonistic activity displayed positive chemotactic responses towards TREs and their three main components (nicotine, scopoletin, octadecane) and its enhanced chemotaxis were induced by these substances in a concentration-dependent manner. Furthermore, following GC–MS and chemotaxis analysis, nicotine was selected as the target for evaluation of the effect on NXHG29 regarding antagonism, growth, root colonization and biocontrol efficiency. Results of in vitro studies showed that nicotine as a sole carbon source could enhance growth of NXHG29 and significantly increased the antagonism of NXHG29. We also demonstrated that nicotine exerted enhancing effects on the colonization ability of NXHG29 on tobacco roots by combining CLSM observations with investigation of population level dynamics by selective dilution plating method. Results from greenhouse experiments suggested nicotine exhibited stimulatory effects on the biocontrol efficiency of NXHG29 against bacterial wilt and black shank on tobacco. The stimulatory effect of nicotine was affected by the concentration and timing of nicotine application and further supported by the results of population level of NXHG29 on tobacco roots. This is the first report on the enhancement effect of nicotine from TREs on an antagonistic bacterium for its root colonization, control of soil-borne pathogens, regarding the chemotaxis and in vitro antagonism and growth.PubDate: 2018-02-03DOI: 10.1007/s10482-018-1035-7

Authors:Jean Franco Castro; Valeria Razmilic; Juan Pablo Gomez-Escribano; Barbara Andrews; Juan Asenjo; Mervyn BibbAbstract: Streptomyces leeuwenhoekii strains C34T, C38, C58 and C79 were isolated from a soil sample collected from the Chaxa Lagoon, located in the Salar de Atacama in northern Chile. These streptomycetes produce a variety of new specialised metabolites with antibiotic, anti-cancer and anti-inflammatory activities. Moreover, genome mining performed on two of these strains has revealed the presence of biosynthetic gene clusters with the potential to produce new specialised metabolites. This review focusses on this new clade of Streptomyces strains, summarises the literature and presents new information on strain C34T.PubDate: 2018-02-03DOI: 10.1007/s10482-018-1034-8

Authors:Valeria Razmilic; Jean Franco Castro; Francisca Marchant; Juan A. Asenjo; Barbara AndrewsAbstract: Metabolic modelling is a useful tool that enables the rational design of metabolic engineering experiments and the study of the unique capabilities of biotechnologically important microorganisms. The extreme abiotic conditions of the Atacama Desert have selected microbial diversity with exceptional characteristics that can be applied in the mining industry for bioleaching processes and for production of specialised metabolites with antimicrobial, antifungal, antiviral, antitumoral, among other activities. In this review we summarise the scientific data available of the use of metabolic modelling and flux analysis to improve the performance of Atacama Desert microorganisms in biotechnological applications.PubDate: 2018-02-02DOI: 10.1007/s10482-018-1031-y

Authors:Benito Gómez-SilvaAbstract: Our knowledge on the Microbiology of the Atacama Desert has increased steadily and substantially during the last two decades. This information now supports a paradigmatic change on the Atacama Desert from a sterile, uninhabitable territory to a hyperarid region colonized by a rich microbiota that includes extremophiles and extreme-tolerant microorganisms. Also, extensive reports are available on the prevalent physical and chemical environmental conditions, ecological niches and, the abundance, diversity and organization of the microbial life in the Atacama Desert. This territory is a highly desiccated environment due to the absence of regular rain events. Liquid water scarcity is the most serious environmental factor affecting the Atacama Desert microorganisms. The intense solar irradiation in this region contributes, in a synergistic fashion with desiccation, to limit the survival and growth of the microbial life. In order to overcome these two extreme conditions, successful microorganisms, organized as microbial consortia, take advantage of (a) the physical characteristics of lithic habitats, which provide sites for colonization on, within or below the rock substrate, the attenuation and filtration of the intense solar irradiation and, the collection of liquid water from incoming fog formations and by water vapour condensation and deliquescence on or within their surfaces, and (b) the biological adaptations of members of the microbial communities that allow them to synthesize hydrophilic macromolecules, antioxidants and UV-light absorbents. Lithic habitats have been considered specialized shelters where life forms can reach protection at environments subjected to extremes of desiccation and solar irradiation, here on Earth or elsewhere. This review is an overview of part of the scientific information collected on lithobionts from the Atacama Desert, their rock substrates and their strategies to cope with extremes of desiccation and intense photosynthetic active radiation and UV irradiations.PubDate: 2018-02-01DOI: 10.1007/s10482-018-1033-9